THE battle for the Conservative crown gets serious today when the main contenders, Boris Johnson and Theresa May, are set to enter the fray after Scots-born cabinet minister Stephen Crabb launched his own bid, emphasising the fears he had over the future of “our divided United Kingdom”.

An attempt earlier this week to bring the two Tory heavyweights together on a joint ticket failed after a meeting between them did not materialise; the former London mayor was said to have been kept waiting for 20 minutes by the Home Secretary, who failed to turn up.

A spokeswoman for Mrs May said: “Theresa is in it to win it; she does not want any deals. She would rather lose than do any deals.”

Mr Johnson, the bookies’ favourite to win, is said to have at least 100 of the 330 Tory MPs supporting him. MPs whittle down the candidates to two, who then face off in a vote of the 150,000 or so party members. The new leader is expected to be announced by September 9.

In an intriguing development, the wife of Michael Gove urged her husband to play hardball with his fellow Brexiter Mr Johnson before making any promises of support in an email she inadvertently sent to a member of the public.

Sarah Vine said the Justice Secretary must secure a specific guarantee about his future before making any deal. “Without that,” she warned, “you have no leverage…Do not concede any ground. Be your stubborn best. Good luck."

Mr Crabb, Inverness-born, who lived part of his early life on a Greenock council estate before moving to South Wales, joined fellow Remainer Business Secretary Sajid Javid, the son of a bus driver, on a joint ticket, representing the "blue collar" alternative to Old Etonian Mr Johnson.

In his speech announcing his candidacy with the slogan “A Plan for Unity and Opportunity”, the Work and Pensions Secretary said how he wanted to be the One Nation candidate, who represented a modern, compassionate and reforming Conservative Party.

He told an audience of MPs and journalists in central London that the geographical split underlined by the EU referendum vote left him “really worried about the future of our divided United Kingdom,” stressing: “A United Kingdom without Scotland is not the United Kingdom; a Great Britain without Scotland is not Great Britain.”

He promised to set up an advisory council, which would not only include UK Government ministers but also First Minister Nicola Sturgeon, representing the Scottish Government, to help guide the UK through the challenges of negotiating Brexit.

Mr Crabb, who branded himself the “underdog,” placed much emphasis on his background – state school educated and raised by a single mother – contrasting it to Mr Johnson’s. He stressed how he wanted a society where it did not matter what kind of school people went to.

He also took a swipe at the former London mayor’s rugby analogy about wanting to be prime minister, when Mr Johnson said if the ball “came loose from the back of the scrum” he would take it. Mr Crabb, 43, a keen rugby player, said life had taught him to “take hold” of the ball and run with it.

The Secretary of State made clear controlling immigration would be a “red line” in the Brexit negotiations. “One message that came through louder than any other in the vote last week is that the British people want to take control of immigration… Brexit needs to do what it says on the tin.”

Meantime, Scot Liam Fox, a former Glasgow GP, who served as defence secretary for 18 months at the start of the coalition government, has also thrown his hat into the ring. The leading Leave supporter, a right-wing Atlanticist, lost out to David Cameron in the 2005 contest.